Introduction

The very phrase ‘broken hearts’ is a flexible expression for many sources of inner anguish, bereavement or disappointment, and it can also mean what it says. The heart is a mechanical pump, and pumps break. The ancients held that the heart was the seat of the soul, so a broken spirit became a broken heart. This distinction will be vital when we try to comprehend the last years of Gustav Mahler, but first let us consider the workings of this complex organ (see Fig. 3).

The heart is made up of specialised muscle (myocardium). It is divided into two upper, low-pressure and thin-walled chambers (atria) and two lower, thick-walled and high-pressure chambers (ventricles). Huge veins bring stale blood back to the right side of the heart, which then pumps the blood through the lungs, where it is revitalised with oxygen, returning afresh to the left side. The oxygenated blood is then pumped, in systole, through the aorta, whose branches bring oxygen to all other parts of the body. If your blood pressure is 130/70 then the systolic pressure is 130 and the diastolic 70, which is a healthy reading.

The heart is lined internally by a membrane (endocardium) and surrounded by a membranous sack (pericardium). During our embryonic development, parts of the endocardium specialise to form one-way valves between the chambers. For example, the aortic valve controls the exit from the left ventricle. Like any other big muscle the myocardium itself needs a good blood supply, and that is supplied by the coronary arteries. The heart is an electrically activated pump; accordingly a band of electrical conducting nerve tissue traverses the central septum within the heart. If it activates seventy systolic beats a minute, the pulse rate is seventy.

So what can go wrong with these excellent arrangements? Th e answer is a lot, of which the following is a very simplifi ed summary.